by DK
Root observed that the Blue-gray Gnatcatcher feeds on insects that live on oak leaves. By analyzing stomach contents, he showed that several other birds also consume oak-leaf insects and proposed that these oak-leaf feeding birds could be grouped into a “guild”—the “oak-foliage gleaners guild”—because they exploited the same resource.
The Blue-gray Gnatcatcher is a member of a guild of small birds that eat insects living on oak trees. Other members of the guild include Hutton’s Vireo and Oak Titmouse.
Shared resources
Root defined a guild as a group of species that “exploit the same class of environmental resources in a similar way.” It does not matter whether species in a guild are related or not—all that matters is how they use their environment. They do not even have to occupy the same niche; they just have to use the same resource.
Guilds are typically identified by the food resource they have in common, although it could be any other resource that they share. Sharing the same resource means that guild members often compete with one another, but they are not necessarily in constant competition. For example, although they may compete for the same food, on other occasions they might cooperate to deal with predators.
The guild concept was a major breakthrough in thinking about connections between organisms in ecosystems. The theory implied that the entire functioning of an ecosystem could be understood by identifying all the guilds within it. Although that was potentially a huge undertaking, ecologists have now managed to identify many more guilds that confirm links between species. For example, the birds of North America can be grouped into guilds of gleaners, excavators, hawkers, aerial chasers, and scavengers.
“…does it matter that a particular insect species is captured by a silken spider web as opposed to a bird’s beak?”
Charles Hawkins and James MacMahon
Broad associations
In the rush to identify guilds, there was some confusion over just what the term meant. By the 1980s, the American ecologists Charles Hawkins and James MacMahon felt the need to redefine the term. They argued that the words “in a similar way” should be dropped from Root’s original definition. It does not matter, they maintained, whether an organism removes a tree leaf to build a nest or for food. It is the resource of the tree leaf that matters rather than the way it is utilized. Either way, the leaf-users belong to a common guild because they are exploiting the same resource.
RICHARD B. ROOT
American biologist and ecologist Richard Root was born in Dearborn, Michigan, in 1936. He grew up on a farm, exploring nature and longing to know “how the woods worked.” By the time he completed his doctorate at the University of Michigan, Root was already a knowledgeable ecologist. His 1967 thesis on the Blue-gray Gnatcatcher, in which he introduced the key concept of the guild, cemented his reputation. Root was invited to join the staff of Cornell University, where he taught biology and ecology. While there, he researched the relationship between arthropods (a large group of invertebrates including insects and arachnids) and goldenrod flowers. Root received many awards during his career, including the Ecological Society of America’s Eminent Ecologist award in 2003 and its Odum award in 2004.
Key works
1967 “The niche exploitation pattern of the Blue-gray Gnatcatcher”
See also: Evolution by natural selection • Predator–prey equations • Optimal foraging theory • Animal ecology • Open community theory • Niche construction • Metacommunities
IN CONTEXT
KEY FIGURES
Fred Urquhart (1911–2002), Norah Urquhart (1918–2009)
BEFORE
1883 The Bird Migration and Distribution recording program starts in the US.
1966 The North American Breeding Birds Survey, conducted by volunteers, begins in Maryland.
AFTER
2007 The Global Biodiversity Information Facility (GBIF) launches a global online portal for collecting data on plants and animals from citizen scientists and professionals.
2010 The eBird online project, created in the US in 2002 by the Cornell Laboratory of Ornithology for volunteers to report real-time bird sightings, becomes a global survey.
Citizen science is research and observation carried out by nonprofessional individuals, teams, or networks of volunteers, often in partnership with professional scientists. It is based on an appreciation that the scientific community should be responsive to the environmental concerns of society as a whole, and an understanding that citizens can produce reliable scientific evidence that leads to greater scientific knowledge. The involvement of ordinary people allows research bodies to accomplish projects that would be far too expensive or time-consuming to run otherwise.
Migratory birds in North America use paths that can be divided into four north–south zones, called flyways—Pacific, Central, Mississippi, and Atlantic. Citizen scientists can play a key role in recording the birds as they stop to feed or rest along the way, during their flights north in spring and south in fall.
“Butterflies—millions upon millions … carpeted the ground in their flaming myriads on this Mexican mountainside.”
Fred Urqhuart
Early enthusiasts
While the term “citizen science” is relatively new, dating from the 1980s, the concept and practice of using the public to observe the natural world and record data has a long pedigree. In the 1870s, small groups of ornithologists in Germany and Scotland began to collect reports on the fall migration of birds, the Scottish enthusiasts using lighthouses around the coast as observation posts. Then, in the early 1880s, the idea of collective observation was extended onto a national scale by American ornithologist Wells Cooke, who began a project to show arrival dates for migratory North American birds and provide evidence for migration pathways. Cooke’s project ran until World War II, gathering 6 million data cards on more than 800 bird species and utilizing 3,000 volunteers at its peak. In 2009, the North American Bird Phenology Program began to digitize the data from the cards, which has provided valuable evidence of changed bird migration dates and routes resulting from global climate change.
The world’s longest-running citizen science survey is the Christmas Bird Count (CBC), held each year in the US. Christmas “side hunts” of birds were a popular pastime in many rural districts of the US in the 19th century, regardless of whether the birds were suitable for eating. In 1900, Frank Chapman, an officer of the Audubon Society—named after American ornithologist and painter John James Audubon—proposed counting birds, rather than shooting them. He encouraged 27 birdwatchers to participate in the first event, and the counts then grew every year. In 2016–17, 73,153 observers submitted counts from 2,536 different locations in North and Latin America, the Pacific, and the Caribbean. The data on the distribution and number of birds has provided a huge data set for ecologists, allowing comparison over time and between habitats.
Observations of birds made and recorded by “citizen scientists” in parks and gardens can provide ecologists with vital data on many species, such as the European Goldfinch.
In search of the monarch
Perhaps the most celebrated act of citizen science was one that set out to solve the mystery of where the migrating monarch butterfly went in winter. In 1952, a Canadian couple, zoologists Fred and Norah Urquhart, who had long been fascinated by the butterfly, set up a tagging scheme in an attempt to find where the insect ended its journey after setting out from southern Canada and the northern states of the US in fall. They enlisted the help of a small group of “citizen scientists” to help tag the wings of the butterflies and report sightings. From a dozen or so helpers, their Insect Migration Association, as it became known, grew to hundreds of volunteers who persisted for years, tagging hundreds of thousands of monarchs with the message “Send to Zoology, University of Toronto.”
Despite the Urquharts’ best efforts, the trail went cold in Texas. Finally, on January 2, 1975, two amateur naturalists, Ken Brugger and Catalina Aguado, discovered the butterfl
ies’ wintering site in montane forest north of Mexico City. No tagged monarchs were found, however, and it was not until the following January that the Urquharts found one—tagged by two schoolboys in Minnesota the previous August. Citizen science had provided the hard evidence that the butterflies migrated from North America to Mexico. Now it is known where millions of monarchs spend the winter, the emphasis has changed to tracking their movements each spring and fall. Thousands of people in Mexico, the US, and Canada are helping build an ever clearer picture of what routes the monarch follows and how it deals with changing weather patterns.
Monarch butterflies form a cluster to stay warm during migration. Tagging by volunteers revealed the monarch’s migratory routes, and continues with the annual “Monarch Watch.”
FRED and NORAH URQUHART
Born in 1911, Fred Urquhart grew up near a railroad line on the edge of Toronto, Canada, and became intrigued by the monarch butterflies that laid their eggs close to the track. After graduating in 1937 from the University of Toronto with bachelor’s and master’s degrees in biology, Urquhart began to research the butterfly. Having taught meteorology to pilots during World War II, he returned to the university to lecture zoology and married Norah Roden Patterson, another Toronto graduate, who joined his quest to find the monarch’s winter home. Fred Urquhart also worked as Curator of Insects and Director of Zoology and Paleontology at the Royal Ontario Museum. In 1998, Fred and Norah Urquhart were awarded their nation’s highest civilian award, the Order of Canada.
Key works
1960 The Monarch Butterfly
1987 The Monarch Butterfly: International Traveler
Citizens march on
More volunteer-based projects were launched during the 1960s and 1970s, including the North American Breeding Bird Survey, the British Nest Records Card project, and a survey of sea turtle egg laying in Japan. In 1979, the Royal Society for the Protection of Birds (RSPB) launched the Big Garden Birdwatch in the UK, which did not even require people to leave their own homes, but simply to record what they saw in their gardens, backyards, or streets. By 2018, more than 500,000 people were participating, recording 7 million birds. The vast amount of data gathered can now be compared for every year back to 1979. Without public help, this would simply not be possible.
In 1989, the term “citizen science” first appeared in print, in the journal American Birds. It was used to describe a volunteer project sponsored by the Audubon Society that sampled rain for acidity. The aim of the project was to raise awareness of the acidification of rivers and lakes that was killing fish and invertebrates, and, indirectly, the birds that preyed on them. It was also designed to put pressure on the US government, which soon after introduced the 1990 Clean Air Act.
Citizen science has also proved its worth for marine conservation. In the Bahamas, a report in 2012 on declining numbers of the queen conch, a large sea snail, led to the formation of “Conchservation,” a campaign that encourages locals to tag conches. Another project, set up in the US in 2010, at the University of Georgia, uses an app, the Marine Debris Tracker, to record sightings of debris in the ocean. Understanding patterns of trash buildup in the world’s seas helps scientists to track how it is transported by currents and where to concentrate removal efforts for maximum effect.
The advent of new technology has led to a proliferation of citizen science projects. Online recording systems allow people to log sightings of anything from stag beetles to wildflowers or migrating birds. In the UK, for example, the Greenspace Information for Greater London (GiGL) website, created by the National Biodiversity Network, allows people to submit records online or by phone, adding to a database used by scientists working to conserve species and habitats.
Limitations and potential
Some ecology research projects are beyond the reach of untrained amateurs because they require too high a degree of skill, or technology that is too complex or expensive. People unfamiliar with scientific methods may also introduce bias into recordings, such as by the omission of a species that cannot be identified.
Most simple citizen science tasks, though, require no training, and some other, more complex, procedures can be tackled after basic tuition. People are often attracted to citizen science precisely because they gain new skills in the process. Increasing pressure on Earth’s natural environments and resources creates an ever greater need for data that records presence, absence, and change in species, their habitats, and the wider ecosystems. Projects such as Zooniverse, the world’s largest citizen science platform, help fill this need, accumulating data from around 1.7 million volunteers worldwide. Such projects will be an invaluable resource for conservation organizations, research institutions, nongovernment agencies, and governments for years to come.
“Science should be dominated by amateurship instead of money-biased technical bureaucrats.”
Erwin Chargaff
Austro-Hungarian biochemist
Young volunteers at Siyeh Pass, in the state of Montana, record their sightings of mountain goats for the high country citizen science project in the Glacier National Park.
Painting the complete picture
Citizen scientists are now the biggest global providers of data on the occurrence of living organisms. Data is easier than ever to submit and artificial intelligence (AI) algorithms can process data in minutes where once it would have taken weeks. For example, if a person records sightings of birds coming to a garden feeder and sends a report from a phone to Cornell University’s eBird website, the information is compared with previous data on factors such as population numbers and migration routes. More than 390,000 people have submitted millions of bird sightings to eBird from nearly 5 million locations around the world. This data is fed into the Global Biodiversity Information Facility (GBIF, coordinated in Denmark), which collects information on plants, animals, fungi, and bacteria. GBIF now contains more than 1 billion observations, and the number is growing daily.
See also: A system for identifying all nature’s organisms • Big ecology • The distribution of species over space and time
IN CONTEXT
KEY FIGURE
Robert May (1936–)
BEFORE
1798 Thomas Malthus argues that human populations will increase at an ever-faster rate, inevitably causing suffering.
1845 Belgian demographist Pierre-François Verhulst argues that checks to population growth will increase in line with population growth itself.
AFTER
1987 Per Bak, Chao Tang, and Kurt Wiesenfeld, a research team in New York, describe “self-organized criticality”—elements within a system interacting spontaneously to produce change.
2014 Japanese ecologist George Sugihari uses a chaos theory approach called empirical dynamic modeling to produce a more accurate estimate of salmon numbers in Canada’s Fraser River.
Chaos theory—the idea that predictions are limited by time and the nonlinear nature of behavior—took hold in the 1960s. American meteorologist Edward Lorenz observed the effect in weather patterns, and described it in 1961. Since then, the theory has been applied to many sciences, including population dynamics.
Chaotic populations
In the 1970s, Australian scientist Robert May became interested in animal population dynamics, and worked on a model to forecast growth or decline over time. This led him to the logistic equation. Devised by Belgian mathematician Pierre-François Verhulst, this equation produces an S-shaped curve on a graph—showing population growing slowly at first, then rapidly, before tapering off into a state of equilibrium.
May experimented with Verhulst’s formula to create the “logistic map,” which showed the population trends on a graph. Although it created predictable patterns at the lowest rates of growth, May found that the logistic equation produced erratic results when the growth rate was equal to or above 3.9. Instead of producing repeating patterns, the map plotted trajectories that appeared completely random. May’s work showed how a simple, constant equation could
produce chaotic behavior. His logistic map is now used by demographers to track and predict population growth.
“Chaos: when the present determines the future, but the approximate present does not approximately determine the future.”
Edward Lorenz
See also: Predator–prey equations • Non-consumptive effects of predators on their prey • The Verhulst equation • Metapopulations
IN CONTEXT
KEY FIGURE
James H. Brown (1942–)
BEFORE
1920 Swedish ecologist Olof Arrhenius produces a mathematical formula for the relationship between area and species diversity.
1964 British entomologist C.B. Williams documents patterns of species abundance, distribution, and diversity in his book Patterns in the Balance of Nature.
AFTER
2002 British ecologists Tim Blackburn and Kevin Gaston argue—contrary to some—that macroecology should be treated as a discipline distinct from biogeography.
2018 A team of scientists uses practical macroecological methods to show that bird species living on islands have relatively larger brains than their mainland relatives.
Scientists seeking faster ways to analyze and counter the many threats to plant and animal populations increasingly turn to macroecology. The term, coined by American ecologists James Brown and Brian Maurer in 1989, describes studies that examine relationships between organisms and their environment across large areas to explain patterns of abundance, diversity, distribution, and change.
